Related Party Transactions (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Polsinelli
Related Party Transaction [Line Items]
Legal services obtained	$ 1.1	$ 0.2	$ 1.7	$ 0.6
Accounts payable for legal services	1.1	0.3	1.1	0.3
Family member of the Company's Executive Vice President \| Legal services from Segal McCambridge Singer & Mahone
Related Party Transaction [Line Items]
Legal services obtained	$ 0.2	$ 0.1	$ 0.4	$ 0.3

Amount for accounts payable to related parties.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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